HMG-14 and HMG-17 are ubiquitous non-histone chromosomal proteins that bind to nucleosome core particles. They form a family of chromosomal proteins that have been reported to bind active chromatin. To understand the in vivo function of these proteins, we disrupted both HMG-14a and HMG-17 in an avian B-cell line DT40. Our results indicate that the knockout cells show no obvious change in phenotype with respect to the parental DT40 cells. Furthermore, no compensatory changes in HMG-14b or histone protein levels were observed in cells lacking both HMG-14a and HMG-17. Upon 2-D gel electrophoretic analysis, a majorly expresssed protein was found to be activated in the knockout cells. Mass spectrometry is going to be used to identify the protein.